The construction is missing, so i have attached it.
Answer:
Use the incenter to determine the center to construct the circle.
Explanation:
From the attached image, we can see that the 3 bisector of the three interior angles in the triangle intersect at a point. This point is known as the incentre of the triangle.
Now, to draw an inscribed circle inside the triangle, we will draw a perpendicular line from the incentre to any of the 3 sides and we will use the incentre as centre to draw the circle to touch each of the 3 perpendicular points.